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Data collection and totalling info
Hello every body,
I am a new user and I am planning to use the device D103 to monitor production and usage of solar and grid energy.
I will use API’s and PERL scripts to receive data from the device.
Then load the data into Round Robin Database and use RRD graphing capability to generate PNG graphs to display.
The issue I see (and this is also on MAIC dash board) is that the energy values are all time cumulative (they always increase) so in order for me to know how much energy was generated/used in a day/month or year, I need to save the value at the end of the previous period (day/month/year) and subtract from the every increasing counter.
Is this so? Or there is a way to see daily/monthly/yearly values? The graphs buttons only change the data resolution not the amount of data entering in the period.
Is there a way for me to program a dashboard to display energy produced used in a day?
Also the amp dial widget when there is a reverse current do not show reverse/negative value, they always show positive values even if the reverse current flag is active. Is this a bug or intended behaviour? How to display negative value for reverse current?
Thank you for your help
Kind regards
Fabio
Excellent and timely answers helping undertand the logic of the system. Thanks!
Сервис поддержки клиентов работает на платформе UserEcho
If you use our Dashboard:
- [Wh]-Energy - cumulative energy value, always increases
- [W]-Power - energy per period (hour/day/month) Switch graphs and widgets using the navigation panel.
See all articles about Dashboard:
https://support.smart-maic.com/en/knowledge-bases/2-main/categories/8-dashboard-and-server/articles
The current value is always positive, this is done on purpose.
To determine reverse energy there are parameters (in the extended version):
[rWh]-Reverse Energy
[rW]-Reverse Power
If you use API, then yes, to determine the energy for a period you need to use the [Wh]-Energy value and subtract the
current value from the previous value.
Thank you for your reply.
I believe there is a bit of uncertainty between power and energy.
Power is an instant value: I am now using 1kW of power ... energy is the integral in dt of such value (1kW used for one hour is 1 kWh) so using 1000 W for 1 second is 0.27777 Wh.
So I cannot use instant power to evaluate energy day because I cannot integrate for time in the widgets and even if possible the time resolution (5 sec) would be too imprecise.
Power and energy and their reverses tell me noting (may be just a little) about current. In order to calculate current from reverse power I should calculate dividing by voltage, and this would be a little imprecise (I also should take into the account the power factor).
Its is not clear to me why current does not have a sign. Understood it is on purpose but why?
If I might suggest:
Current should have a sign (minus for reverse) so it is know where it flows.
The device should/could publish 3 (6 for extended version) additional values for each line:
last day energy
last month energy
last year energy
This could be set to current energy values when the day/Month/Year date value changes.
The data is available on server.
But in order to extract it easily (to subtract from the cumulative value), there should be a function allowing extraction of the stored data at 00:00 of the previous day, 00:00 of first day of each month and 00:00 1 Jan of each year.
I am not sure if this can be easily done in server APIs but it appears it cant be done in the dash board.
And also on server, after a day, only hourly data is available to the exact value needs to be picked up within a day from change of month, change of year, change of day. Maybe those should be stored longer (it is just one data point ...) and made available for calculation in dashboard and maybe API requests.
Just a suggestion but it would greatly improve the usefulness of graphs and it should be rather easy to implement in firmware. Also because it is not very easy to implement it via dashboard. Happy to experiment with you if you wish to develop it.
Further selecting the data period does not change the way data is collated, it only change the x axis scale and the number of samples which are replaced with their average .... so once again not useful for this purpose.
Thank you for considering this information and your continued support.
Cheers
Fabio
It is important to understand how the data from the smart-MAIC energy monitor is stored at different time intervals.
It is especially important to understand the calculation principle for the [W]-Power parameter when it contains electrical power [Watt] or electrical energy [Watt*hour].
Designation
rW1 rW2 rW3 and TrW (total)
Wh1 Wh2 Wh3 и TWh (total)
cumulative electricity meter [Wh]
rWh1 rWh2 rWh3 and TrWh (total)
cumulative electricity meter [rWh]
Ok,
Thank you very much, So power becomes energy while energy always remains energy.... a bit confusing.
In any case, if I understand correctly, this is only available from the server while the device provides only Real-Time.
Cheers
Fabio
Yes, this is only available from the server.
For Real-Time: [W]-Power contains the Active Power [Watt]
For Hour/Day/Month: [W]-Power contains the Active Energy for the period [Watt*hour]
If you use API, then yes, to determine the energy for a period you need to use the [Wh]-Energy value and subtract the
current value from the previous value.